1. Field of the Invention
The present invention relates to a disk driving device incorporated into an electronic computer or a word processor for recording information in a disk and reproducing the recorded information and, more specifically, to a disk clamping mechanism for such a disk driving device.
2. Description of the Prior Art
A disk driving device clamps a disk inserted between a hub and a spindle by pressing the hub toward the spindle and rotates the disk by driving the spindle for rotation by means of a motor. Information is recorded in the disk or the information recorded in the disk is reproduced by rotating the disk between a recording/reproducing head mounted on a carriage movable in the radial direction of the disk and another head or pad attached to a swingable arm swingably joined to the carriage.
FIG. 6 illustrates the constitution of a conventional disk clamping mechanism by way of example. In FIG. 6, there are shown a chassis 40, a door frame 41 connected to the chassis 40 by means of a spring plate 42, a guide pin 43 projected from the door frame 41 perpendicularly to the door frame 41, a hub 44 slidably fitted on the guide pin 43, a compression coil spring 45 provided on the guide pin 43 between the door frame 41 and the hub 44 so as to urge the hub 44 away from the door frame 41, a spindle 46 which is driven for rotation, a disk 47, a carriage 48 capable of reciprocating in the radial direction of the disk 47, a recording/reproducing head 49 mounted on the carriage 48, an arm 50 connected to the carriage 48 by means of a spring plate 51, a pad 52 attached to the extremity of the arm 50 so as to be disposed opposite to the recording/reproducing head 49, a pressure spring 53 urging the arm 50 in the closing direction, and an arm retaining part 54 provided integrally with the door frame 41 and engaging the lower surface of the arm 50 to retain the same.
When the door frame 41 is turned on the spring plate 42 in the closing direction indicated by an arrow A, after inserting the disk 47 into the disk clamping mechanism, the hub 44 is lowered as the door frame 41 is turned, and thereby the disk 47 is aligned correctly with the spindle 46 and the disk 47 is held correctly between the hub 44 and the spindle 46. Since the arm retaining part 54 is lowered as the door frame 41 is turned in the direction of the arrow A, the arm 50 retained by the arm retaining part 54 is turned accordingly by the resilient force of the spring plate 51 and that of the pressure spring 53, so that the disk 47 is pressed against the recording/reproducing head 49 with the pad 52. Thus, disk clamping operation by means of the hub hub 44 and disk pressing operation by means of the pad 52 are achieved simultaneously by turning the door frame 41.
The spring constant and the size of the compression coil spring 45 are designed appropriately so that the hub 44 is pressed against the spindle 46 at an appropriate pressure. However, the actual pressure applied to the hub 44 is often different from the design pressure due to the dimensional allowances in the associated parts and the difference of the actual rigidity of the associated parts from the corresponding design rigidity. An excessive pressure causes the clamped portion of the disk 47 to be worn, while an insufficient pressure causes the disk 47 to slip relative to the spindle 46, and thereby the disk 47 is unable to be driven correctly. Thus, the conventional disk clamping mechanism requires troublesome and different adjustment for adjusting the pressure for pressing the hub 44 against the spindle 46 at a value within a satisfactory range of accuracy.